The present invention is directed to an improved sleeve valve for flexible bags. Such flexible bags are used to package granular materials, such as fertilizers, seeds, etc. and are provided with a bottom wall, a top wall, side walls and end walls. The end walls as well as the bottom and top walls are adapted to be folded along predetermined fold lines so that the bags may be flattened for shipment and storage.
One corner of the top wall is provided with an open mouth which is adapted to receive the filler spout of a product-dispensing machine. Mounted within the open mouth and adapted to receive the filler spout is a sleeve valve. Such sleeve valves usually consist of a flexible tubular plastic sleeve and a backing panel. One side of the tubular plastic sleeve is affixed to the backing panel and the opposite side is affixed to the lower portion of the open mouth. The rear portion of the tubular sleeve is not affixed to either the backing panel or to the mouth of the container so that it hangs loosely within the bag. After the bag is filled, the rear portion of the tubular sleeve is bent back by the contents within the bag so that it seals the mouth to prevent the contents of the bag from sifting out of the bag.
An example of such a flexible bag and sleeve valve is described and shown in U.S. Pat. No. 4,316,574 of George Lepisto, owned by the assignee of the present invention and application.
Heretofore, the tubular sleeves used for such sleeve valves have been solid and uninterrupted throughout their peripheries and the paper backing panel to which such tubular sleeves were attached were likewise uninterrupted. It has been found that such sleeves do not sometimes seal as effectively as they should. Furthermore, in existing bags, the tubular plastic sleeve is adhered to the paper backing panel by a uniform layer of adhesive which increases the cost.